1. Field of the Invention
This invention is generally related to grinding mechanisms, and more particularly to grinders or mills for grinding materials, such as spices and grain.
2. Description of the Related Art
Mills for grinding materials such as spices and grains are common household items. For example, pepper mills are ubiquitous in households and restaurants. Such mills generally include a housing or body which presents an attractive outward appearance, and which forms a chamber or reservoir for holding a material (e.g., peppercorns) to be ground. The body also typically encloses a grinding mechanism in fluid communication with the chamber, the grinding mechanism grinding the material and dispensing the ground material through an opening or exit in the bottom of the body. The grinding mechanism typically includes an actuator (e.g., crank arm, operating lever), a grinding bit, an engagement surface for cooperating with the grinding bit to grind the material therebetween, and a transmission drivingly coupling the actuator to the grinding bit. Often the body will form a second chamber, separate from the first chamber, for holding a material that does not requiring grinding (e.g., salt).
Most mills are hand operated and may be used by chefs or cooks in the preparation of food, or by servers and/or diners at dining tables. Many mills have a crank arm which is turned continuously and unidirectionally (e.g., clockwise or counterclockwise) with one hand of the user, while the other hand holds the mill in a generally vertical direction such that the ground material drops out of the bottom. Other mills have an operating lever which is reciprocatingly operated (i.e., bi-directionally) with the fingers or thumb of the hand holding the mill.
Typically, the grinding mechanisms fall into two categories, rotary mechanisms and linear mechanisms. Many rotary mechanisms are driven by turning a crank arm directly connected to a drive shaft of the grinding mechanism, which in turn is directly connected to the grinding bit. The crank arm, drive shaft and grinding bit each rotate about respective axes or rotation, the axes being parallel to each other, or even collinear. A number of rotary mechanisms are driven by reciprocating movement of an operating lever. Such rotary mechanisms include a grinding bit axially mounted on a drive shaft, and transmission means in the form of gears for translating the reciprocating motion of the operating lever into rotation of the drive shaft for driving the grinding bit. Again, the axes of rotation of the drive shaft and grinding bits are parallel or even collinear. Linear grinding mechanisms rely on linear movement of the grinding bit to grind the material. Typically, linear mechanisms employ the axial translation of a transmission element, such as a rack, to produce the linear translation of the grinding bit.
Most grinders also include mechanisms for adjusting the space between the grinding bit and the engagement surface to allow the user to select a desired grain size. In rotary mechanisms, the grinding bits are typically conical and having a uniform set of teeth around the periphery of the cone or truncated cone. The space between the engagement surface and the grinding bit may be adjusted by translating the conical grinding bit along its longitudinal axis with respect to the engagement surface. In linear mechanisms, the grinding bit typically takes the form of a straight or beveled surface having a set of uniform teeth. The space between the engagement surface and the grinding bit is adjusted by translating the grinding bit either toward or away from the engagement surface.
It is desirable to reduce the cost and complexity of mills. It is also desirable to produce mills that are sturdy and easy to operate. Further, it is desirable to provide a mill that efficiently and uniformly grinds material to any selected size.